1. Field of the Invention
This disclosure relates to a sensor assembly and, more particularly, to a adjustable sensor assembly for determining the location of at least one edge of print media.
2. Description of the Related Art
Printer sensors are typically used to determine the presence and location of the edge of the print media during operation. The printer requires a reference position in order to begin printing. This ensures that an appropriate location is available in the print area and that edge or over the edge printing does not occur. It is also desirable to be able to distinguish between labels, for example, on a continuous supply roll. The printer, therefore, can determine the appropriate start and finish locations on the print media in order to place a printed bar code, for example, on the appropriate label and advance the print media to the next location in a reliable and efficient manner.
Sensors are used to determine the position of a label within a print head, that is, the distance that the print media has advanced. Traditional optical means of detecting the position of labels, for example, include a "through beam" system wherein an emitter is placed on one side of the label and a detector is placed on the reverse side. There are two methods of using "through beam" technology. These include gap and stripe indication. In the gap indication method light is passed through the print media and gaps between labels are sensed as a change in light intensity.
Stripe indication senses a black stripe printed on either side of the print media. When the indicator stripe is present, the light from the emitter does not pass through the labels and is not detected by the detectors. Stripe sensing can also be performed from one side of the media. A light source shines on the print media and the reflection is sensed to determine the position of the print media.
In order for the position sensor to work properly the black stripe must be in line with the sensor. When various print media sizes are used, printers are typically provided with an additional sensor at each location for each size of the print media. This increases the complexity and cost for the printer, however, since numerous sensors are needed to accommodate print media of different sizes. Some printers typically require that the single sensor be removed and remounted each time a different size media is used.
Printer versatility is desirable. Therefore a need exists for a sensor which can be easily adjusted to allow the use of various sized print media in the printer. A further need exits for such a sensor wherein the sensor is readily accessible and therefore does not require difficult disassembly steps in order to adjust the sensors position.